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I'm using the Eevee engine and the fireworks are emissive particles, bloom is turned on. I tried both eevee and cycles, I want to use eevee though. I tried PNG with RGBA color, 8bit and 16bit color, no compression. I also tried TIFF with RGBA color, 8bit and 16bit color, no compression.

I want to render the images with a transparent background while keeping the color of the fireworks. In the viewport it looks normal, but when I render it and save the image it loses the color in the fireworks over the transparent background.

Here is a blend file of the fireworks and just simple cubes since sharing the models in the blend file is against ToS, but it does the same thing here. https://drive.google.com/file/d/1O-6VudxGP-Y_7jO09FVzM4IRjJEtTHQZ/view?usp=sharing

Rendered Image

Viewport Image

Harry McKenzie
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VoidAnomaly
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  • wow that is really odd... the render looks fine but when saved as image it gets corrupted. does not make any sense. – Harry McKenzie Aug 26 '23 at 16:49
  • Going on over a decade at this point, but I’ll keep repeating it. The design of Blender’s encodings is broken. You need associated alpha, and some dimwit disabled all associated alpha way back, in all encodings except EXR. Some dimwits will try to convince that they made a wise choice. They did not. TIFF should work, but because of dimwit design it doesn’t. PNG is horribly broken and can never work. Use EXR is the only option, and it will work. – troy_s Aug 27 '23 at 03:52
  • EXR doesn't work with the bloom, it has the same issue as the other image formats. Download the blend file and show me how to make it work, if its simpler I'd much rather use that. – VoidAnomaly Aug 27 '23 at 04:11
  • False. It works perfectly fine. There are countless threads here supporting that. Additive “emission” RGB is positive, with zero alpha. – troy_s Aug 27 '23 at 21:21
  • Okay, I see what you mean now, EXR stores bloom the same way a PNG with a black background stores it. So I only have to render two layers instead of three for each collection since the EXR also includes the alpha channel. I included an image of the two node setups, they give the same result, one is using PNG and one is using EXR. https://imgur.com/a/RAP22Tk – VoidAnomaly Aug 28 '23 at 07:35
  • You shouldn't really be compositing with PNGs because they literally cannot represent the "emission" in the file encoding. It's a broken format.

    The EXR will "Just Work" if you load it into Blender separately, and use a basic Alpha Over with some constant RGB set.

    You will see the proper composite, without any janky PNG nonsense. Sadly, because the Blender developers still haven't fixed TIFFs and what not, the only option is EXR. PNG is simply broken, but so is Blender's handling of picture encodings.

     – troy_s Aug 28 '23 at 15:48
  • You also don't need all those adds and such in your composite with the EXR. It's literally about encoded alpha. https://imgur.com/a/lj9SFEV – troy_s Aug 28 '23 at 15:50
  • I swear I tried that at the beginning before asking this question and it didn't work, but it works lol. Thank you. – VoidAnomaly Aug 28 '23 at 18:41
  • Maybe one day Blender developers will fix the damn file encodings for TIFF to support associated alpha, switch TIFF to default, and then the endless barrage of questions here will cease. Until then… help other folks. You can generally find this exact same issue repeated in different ways, once or twice per week. PNG really needs to be punted out to orbit. – troy_s Aug 30 '23 at 00:33

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